I. Field of the Invention
This invention relates generally to the compression section or chamber of a paperboard carton packaging machine having novel compression rollers.
II. Description of the Prior Art
Packaging machines of the type for receiving a one-piece corrugated board blank having a product or lading positioned thereon to be lowered into the machine at an entrance end for formation of a carton from the blank with the lading contained therein are generally known. Such a machine is illustrated and described in the Related Patent. Suitable mechanisms are provided for folding the blank around the lading to form a completed carton which is discharged by the machine into a so-called compression section or chamber. Generally, the length of the compression section is sufficient to receive a plurality of packages from the machine.
During operation of the packaging machine, the compression section thereof is filled with completed cartons arranged in a row. Then, as a next completed carton is pushed into the compression section, it pushes the row of cartons ahead of it and discharges a carton from the discharge end of the machine. During continued operation of the machine, a completed carton fed into the compression section causes one such carton to be discharged from the end of the section. Consequently, the completed carton initially fed into the compression section remains in the section for a certain period of time as it is intermittently pushed along the compression section to the discharge end thereof. This time period in the compression section is required to permit adhesive applied to the flaps of the carton blank while in the packaging machine to dry and set.
In order to achieve proper setting or drying of the adhesive, the cartons in the compression section must be maintained square and in true abutting alignment so that all flaps will remain in proper registry with carton panels during the drying or setting time period. Concurrently, the cartons must be moved along the compression section during the drying period.
In order to achieve the required maintainence of the cartons in true abutting alignment during setting of the adhesive while the carton is in the compression section, the vertical sides of the compression section of prior structures, including that disclosed in the Related Patent, were constructed with parallel rows of vertically arranged rollers formed of a non-yieldable material such as wood or metal. A continuous non-yieldable flat belt or web of rubber, canvas or felt material was trained or positioned around each row of rollers to abut the side walls of the carton as they passed through the compression section of the packaging machine. The non-yieldable belt was such as to produce a line-to-surface interface between the respective carton side walls and the belt by adjusting the distance between the belts to be slightly less than the width of each carton. Such interface has an inherent disadvantage in that cartons may become undesirably compressed or deformed as they move through the compression section. It is necessary for tolerances of the compression section to be variable to accommodate various size cartons which may be formed by the packaging machine. In operation of the prior art structures, the operator of the machine was required to exercise considerable care to be sure that the compression section side walls having the continuous non-yieldable belt were positioned precisely so as on the one hand to maintain the cartons in proper registry while they are in the compression section, and on the other hand, to avoid moving the walls so closely together in an effort to achieve the required restraining of the cartons that the walls thereof were too tightly compressed thereby resulting in damage thereto.
The rollers of the invention provide the required solution to the problems encountered with the non-yieldable rollers and belt utilized in the compression section of the Related Patent. The rollers of the invention are formed with yieldable sleeves such that the belt no longer is required and the rollers themselves form the side walls of the compression section. Further, the yieldable sleeves formed on the outer surface of the rollers of the invention are such that as a carton is pressed against them in the compression section, a planar, surface-to-surface interface or contact between the rollers and the side walls of each respective carton is achieved. The rollers of the invention are such as to properly maintain the cartons passing through the compression section of the packaging machine in square and true abutting alignment as required and additionally, by reason of the soft compressible material on the rollers, adjustments to vary the distance between the walls of the compression section may be made without the danger of moving the walls too closely together which might damage the cartons as they pass through the chamber, as was the case with the prior art structures.
In order to protect the yieldable sleeves of the rollers of the invention from excessive wear which distorts the same and further, to produce a reduced friction, and less adherent surface between the rollers and carton side walls, the sleeves may be covered with protective polyethylene film. The addition of the film does not interfere with the intended performance of the rollers of the invention.